Hi Eric,
I think you're on the right way.
See inline...
On 06/28/2012 04:40 AM, Eric Luong wrote:
> Any suggestions on what to look for with jmap/jhat? I'm unfamiliar
> with the tools. When I run jhat on a heap dump, it comes up with a
> fair number of warnings -- "Failed to resolve object id [some id]" and
> "Failed to resolve object id [some id] for field value (signature
> L)". Not sure what these mean. It might be worth mentioning that I
> had to use -F on jmap; without it, I get the "target process is not
> responding".
That's correct.
>
> Just looking at this snapshot (which is not near the plateau I
> described), it seems the class with the largest total size is "class
> [C" which is obviously not a useful class name.
It's character arrays.
I just took snapshot w/ jmap and opened in jhat.
In the browser I clicked "Heap histogram", now I see types sorted by
number of instances and memory consumption.
When you investigate the problem, pls. take a snapshot when issue occurs
and check the heap histogram. Most probably the problematic object
(which leaks) would be on the top of the list.
> Does that mean it is some anonymous class? Exploring it further, it
> only lists Object as its superclass. There are several other such
> nameless classes. Other information for these classes (ClassLoader,
> Signers, Protection Domain) are all null. Other classes that seem to
> consume the majority of memory are HashMap, HashMapEntry and related
> classes.
Most of the time char[] is at the top of the list, different collections
like HashMap also.
Pls. take a snapshot when the memory issue occurs and check the heap
histogram, may be you'll find some suspicious object on the top. If not
- you can share the snapshot file, I can try to help.
>
> Can you suggest how to approach this using jmap/jhat, and if those
> warnings I received are of any significance?
I also see warnings from jhat, but IMO it's still ok.
You can also check another profiler tools like the one Chris suggested
(visual vm).
Thanks.
WBR,
Alexey.
> Then I will proceed with checking out different memory state snapshots.
>
> Thanks for your help,
>
> Eric
>
> On Mon, Jun 25, 2012 at 6:37 AM, Oleksiy Stashok
> <oleksiy.stashok_at_oracle.com <mailto:oleksiy.stashok_at_oracle.com>> wrote:
>
> Hi Eric,
>
> it would be great if you can monitor the memory usage using some
> profiler tool or jmap/jhat and give us more details on objects
> (object types), which consume memory. You can take several memory
> state snapshots like initial, 1000 clients connected, 2000 clients
> connected, 3000 clients connected, so we can see the dynamics and
> figure out the problem (if there is any).
>
> Thanks.
>
> WBR,
> Alexey.
>
>
> On 06/23/2012 04:48 AM, Eric Luong wrote:
>
> Hello,
>
> I've been testing Grizzly in Glassfish 3.1 by simulating a
> load of thousands of clients using long polling. I found what
> appears to be a bottleneck. As more clients are added, the
> memory usage of the server increases. However, after a
> certain point (2000 clients in my case, but I expect it would
> depend on hardware) the usage seems to taper off and plateau.
>
> I have been trying to figure out why the memory usage
> plateaus. Can anyone offer some insights, or suggest a way to
> investigate further?
>
> Thank-you!
>
> Eric
>
>
>
>